1. Field of the Invention
The present invention relates to an insertion device for inserting into an eye an intraocular lens which is inserted instead of a crystal lens after the crystal lens is extracted because of cataract or inserted into an eye in order to cure abnormal refraction.
2. Description of the Related Art
In the case of a surgery for cataract, the central portion of the anterior capsule of an eyeball is ablated, a clouded crystal lens is removed by an ultrasonic suction apparatus, and then an artificial intraocular lens is placed to the position of the removed clouded crystal lens. When placing the lens in the eyeball, a surgery method for inserting the lens into the eyeball through a small incision by using the flexibility of the lens and thereby deforming the lens into a small shape, e.g. folding the lens is the mainstream. Thereby, astigma after surgery is prevented.
Then, in the case of a surgery, an insertion device is frequently used which deforms the lens into a small shape while moving the lens set in the main body of the insertion device by a pushing shaft and pushes the lens into an eye from the front opening of an insertion cylinder (nozzle) inserted into the incision. This insertion device is used not only for the surgery of cataract but also for a lens inserting surgery for a vision correction treatment.
When the lens is inserted into an eye by using the insertion device, a viscoelastic material such as hyaluronate sodium is introduced into the insertion device as a lubricant so that the lens is smoothly moved and deformed in the insertion device. Moreover, the viscoelastic material has a function of spreading the space of the anterior chamber of the eye into which the lens will be inserted.
Conventionally, a viscoelastic material is introduced from the front opening of the insertion cylinder by using a syringe or introduced from the introducing port provided on the main body of the insertion device (see Japanese Patent Laid-Open No. 2004-351196).
However, when using a viscoelastic material, the following problems occur.
1. The viscoelastic material that entered an eye together with a lens requires difficulty or labor hours to remove the material from the eye due to its viscosity. Therefore, the time required for the surgery is increased.
2. Since a space into which a lens is inserted in an eye is small, when the viscoelastic material enters the eye before the lens, the space is blocked by the viscoelastic material and it is difficult to insert the lens into the space.
3. Most viscoelastic materials including hyaluronate sodium are expensive.
Thus, the viscoelastic material is effective as lubricant, but it also has disadvantages. Therefore, it is requested to use low-viscosity inexpensive normal saline which is generally used for surgeries in place of the viscoelastic material.